This is a note to let you know that I've just added the patch titled
ethtool: reset #lanes when lanes is omitted
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
ethtool-reset-lanes-when-lanes-is-omitted.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit c7846ede2078e5be1a0469f1043363471edf36ce
Author: Andy Roulin <aroulin@xxxxxxxxxx>
Date: Mon Apr 3 14:20:53 2023 -0700
ethtool: reset #lanes when lanes is omitted
[ Upstream commit e847c7675e19ef344913724dc68f83df31ad6a17 ]
If the number of lanes was forced and then subsequently the user
omits this parameter, the ksettings->lanes is reset. The driver
should then reset the number of lanes to the device's default
for the specified speed.
However, although the ksettings->lanes is set to 0, the mod variable
is not set to true to indicate the driver and userspace should be
notified of the changes.
The consequence is that the same ethtool operation will produce
different results based on the initial state.
If the initial state is:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 2
Duplex: Full
Auto-negotiation: on
then executing 'ethtool -s swp1 speed 50000 autoneg off' will yield:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 2
Duplex: Full
Auto-negotiation: off
While if the initial state is:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 1
Duplex: Full
Auto-negotiation: off
executing the same 'ethtool -s swp1 speed 50000 autoneg off' results in:
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 1
Duplex: Full
Auto-negotiation: off
This patch fixes this behavior. Omitting lanes will always results in
the driver choosing the default lane width for the chosen speed. In this
scenario, regardless of the initial state, the end state will be, e.g.,
$ ethtool swp1 | grep -A 3 'Speed: '
Speed: 500000Mb/s
Lanes: 2
Duplex: Full
Auto-negotiation: off
Fixes: 012ce4dd3102 ("ethtool: Extend link modes settings uAPI with lanes")
Signed-off-by: Andy Roulin <aroulin@xxxxxxxxxx>
Reviewed-by: Danielle Ratson <danieller@xxxxxxxxxx>
Reviewed-by: Ido Schimmel <idosch@xxxxxxxxxx>
Link: https://lore.kernel.org/r/ac238d6b-8726-8156-3810-6471291dbc7f@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ethtool/linkmodes.c b/net/ethtool/linkmodes.c
index f9eda596f3014..3d05b9bf34854 100644
--- a/net/ethtool/linkmodes.c
+++ b/net/ethtool/linkmodes.c
@@ -277,11 +277,12 @@ static int ethnl_update_linkmodes(struct genl_info *info, struct nlattr **tb,
"lanes configuration not supported by device");
return -EOPNOTSUPP;
}
- } else if (!lsettings->autoneg) {
- /* If autoneg is off and lanes parameter is not passed from user,
- * set the lanes parameter to 0.
+ } else if (!lsettings->autoneg && ksettings->lanes) {
+ /* If autoneg is off and lanes parameter is not passed from user but
+ * it was defined previously then set the lanes parameter to 0.
*/
ksettings->lanes = 0;
+ *mod = true;
}
ret = ethnl_update_bitset(ksettings->link_modes.advertising,
